Federal Communications Commission Spectrum Policy Task Force, “Report of the Spectrum Efficiency Working Group,” 2002. http://www.fcc.gov/sptf/files/SEWGFinalReport_1.pdf
 C. R. Stevenson, G. Chouinard, Z. Lei, W. Hu and S. J. Shellhammer, “IEEE 802.22: The First Cognitive Radio Wireless Regional Area Network Standard,” IEEE Communications Magazine, Vol. 47, No. 1, 2009, pp. 130-138. doi:10.1109/MCOM.2009.4752688
 A. Goldsmith, S. A. Jafar, I. Maric and S. Srinivasa, “Breaking Spectrum Gridlock with Cognitive Radios: An Information Theoretic Perspective,” Proceedings of the IEEE, Vol. 97, No. 5, 2009, pp. 894-914. doi:10.1109/JPROC.2009.2015717
 T. Luo, F. Lin, T. Jiang, M. Guizani and W. Chen, “Multicarrier Modulation and Cooperative Communication in Multihop Cognitive Radio Networks,” IEEE Wireless Communications, Vol. 18, No. 1, 2011, pp. 38-45. doi:10.1109/MWC.2011.5714024
 J. Lou, T. Luo and G. Yue, “Power Allocation for Cooperative Cognitive Networks,” IEEE 3rd International Conference on Broadband Network and Multimedia Technology, Beijing, 26-28 October 2010, pp. 412-416.
 C. H. Chen, C. L. Wang and C. T. Chen, “A Resource Allocation Scheme for Cooperative Multiuser OFDMBased Cognitive Radio Systems,” IEEE Transactions on Communications, Vol. 59, No. 11, 2011, pp. 3204-3215. doi:10.1109/TCOMM.2011.092011.100197
 L. Li, X. Zhou, H. Xu, G. Y. Li, D. Wang and A. Soong, “Simplified Relay Selection and Power Allocation in Cooperative Cognitive Radio Systems,” IEEE Transactions on Wireless Communications, Vol. 10, No. 1, 2011, pp. 33-36. doi:10.1109/TWC.2010.101810.100311
 W. C. Ao, S. M. Cheng and K. C. Chen, “Power and Interference Control with Relaying in Cooperative Cognitive Radio Networks,” IEEE International Conference on Communications, Cape Town, 23-27 May 2010, pp. 1-5.
 C. Zhao and K. Kwak, “Joint Sensing Time and Power Allocation in Cooperatively Cognitive Networks,” IEEE Communications Letters, Vol. 14, No. 2, 2010, pp. 163-165. doi:10.1109/LCOMM.2010.02.092102
 C. N. Hsu, H. J. Su and P. H. Lin, “Joint Subcarrier Pairing and Power Allocation for OFDM Transmission With Decode-and-Forward Relaying,” IEEE Transactions on Signal Processing, Vol. 59, No. 1, 2011, pp. 399-414. doi:10.1109/TSP.2010.2081982
 L. Vandendorpe, R. T. Duran, J. Louveaux and A. Zaidi, “Power Allocation for OFDM Transmission with DF Relaying,” IEEE International Conference on Communications, Beijing, 19-23 May 2008, pp. 3795-3800.
 W. Ying, Q. Xin-chun, W. Tong and L. Bao-ling, “Power Allocation and Subcarrier Pairing Algorithm for Regenerative OFDM Relay System,” IEEE 65th Vehicular Technology Conference, Dublin, 22-25 April 2007, pp. 2727-2731.
 N. Papandreou and T. Antonakopoulos, “Bit and Power Allocation in Constrained Multicarrier Systems: The Single-User Case,” EURASIP Journal on Advances in Signal Processing, Vol. 2008, 2008, Article ID: 643081. doi:10.1155/2008/643081
 W. Yu and R. Lui, “Dual Methods for Nonconvex Spectrum Optimization of Multi-Carrier Systems,” IEEE Transactions on Communications, Vol. 54, No. 7, 2006, pp. 1310-1322. doi:10.1109/TCOMM.2006.877962
 K. Seong, M. Mohseni and J. M. Cioffi, “Optimal Resource Allocation for OFDMA Downlink Systems,” IEEE International Symposium on Information Theory, Seattle, 9-14 July 2006, pp. 1394-1398. doi:10.1109/ISIT.2006.262075